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(No Model.)

SCREEN.

Patented Feb. 22, 1898. /z-f-:7 '(13 ms uonms Pzzns co. 0104 man, wAsmNsTuN, n. c.

` Nrrnn STATES ATnNr rricn@ SCREEN.

SPECIFICATION forming part of Letters Patent No. 599,468, dated February 22, 18198.

Application filed August 3, 1896. Serial No. 601,429. (No model.)

To all who/n it may concern:

Be it known that I, GEORGE YV. CROSS, a citizen of the United States, residing at Pittston, in the county of Luzerne and State of Pennsylvania, have invented a certain new and useful Improvement in Screens, of which the following is a specification.

The present invention concerns the construction of screening-surfaces, and is directed particularly to that type of screens adapted for the separation of coal, ore, stone, &c., known as revoluble screens, in which the screening-surface is cylindrical in form, the material being fed to the interior thereof and passed over the screening-surface or mesh. As is well known, in this type of apparatus were the interior of the cylinder smooth the material would pass therethrough at considerable speed, governed largely by the pitch of the screen, and owing to the velocity of its travel particles of such size as to be capable of passing through certain perforations would travel over the same and become mixed with particles of a larger size designed to pass through larger perforations toward the lower end of the screen. Means are therefore commonly employed for tumbling or agitating the material in its passage through the screen-such for instance, as an angle-iron bolted or otherwise secured to the margins of the segments of which the screen surface or jacket is composed. Another structure designed for this purpose consists of flanges on the margins of segments. I have found that in practice it is highly desirable not only to tumble or agitate the material in its passage through the screen, but also to deflect it, so that while such material is passing over one round of screen-segments it will be deflected from a straight or spiral line of travel and at once agitated and thrown back at an angle to such line of travel, so as to guard against failure to separate particles designed to be screened in that round of segments. Thus if the first round of segments upon a revoluble screen were provided with a three-quarterinch mesh particles of `such size as to pass through such mesh might in the absence of suitable provision therefor ride upon larger particles and thereby be prevented from being separated from the mass. In the construction contemplated by this invention,

however, the mass after passing over the surface of each segmentis agitated and deflected or turned back from its line of travel, so that it passes over a greater area of screening-surface, and the mass being tumbled and more or less distributed the particles designed to be screened upon that round are thrown directly upon the screening-surface. In accomplishing this object I employ a series of screen-segments in combination with deflecting-lips. These lips are separated and turned inwardly toward the longitudinal axis of the screen. In practice the material after passing over the mesh of one segment is caught by these inwardly-proj ecting lips, and by reason of their curvature and relativity to the line of travel of the material the latter is turned backward against the pitch of the screen, thereby permitting it to again pass over a portion of the mesh of similar size of thenextadjacentscreen-segment. Theselips operate not only to deflect and turn back the material, but also to agitate or tumble it, so

as to preclude the sliding motion of the mass of material being separated, which results in the imperfect sizing of the particles.

The invention is illustrated in the accompanying drawings, in which- Figure l is a plan view of a screen-segment employing my invention. Fig. 2 is a similar View of a portion of the screen-segment, illustrating a slightly different construction of the lips. Figs. 3 ande are detail perspectives of a portion of the structures shown, respectively, in Figs. l and 2. Figs. 5 and 6 illustrate modiiications hereinafter to be described. Fig. 7 is a sectional view of a portion of one round of screen-segments, illustrating the relation of two segments to each other when in position upon the screen-frame; and Fig. 8 is an end view of a screen made up of segments employing the inventiont Referring to the drawings, in which similar letters of reference denote corresponding parts, A designates a screen-segment. This is preferably constructed of sheet-steel. It is provided with a perforated screen-surface a and with imperforate side margins a' and end margins a2. The end margins may be provided with holes a for the reception of bolts, by means of which the segment may be secured to the spider-bands of the screen and the IOO side margins with similar holes a4 a5, by means of which each segment may, if desired, be secured to the edges of the two adjoining segments. The perforations a may be of any desired shape, and, if desired, the Webs surrounding them may be curved or crimped.7 In all these structures save those illustrated in Figs. 5 and 6 the deflecting medium is shown as formed integral with the segment. I shall first describe this construction. The segment as a whole is, as before stated, curved to the arc of the circle, so that a certain number of them (depending upon the diameter of the screen) may constitute one round -that is to say, one section-of the cylinder. One edge of the segment instead of terminating in a straight narrow imperforate margin Vis bent inwardly at B on a straight line coinciding with one end of the end margins, so as to form a shoulder b. This permits the level margin of the next adjacent segment to fit snugly against the exterior of the shoulder, and where such margin is perforated a bolt may be passed through the perforation 0.5 of one segment and through the perforation a4 of the next adjacent segment and provided with a nut or other means for holding both segments in their proper relative positions.

B designates a series of deflecting-lips. In the structure now being described these are integral with the segments. In practice it has been found desirable to form the whole segment from a plate of sheet-steel, one side of the segment being provided with an imperforate margin considerably wider than that upon the other side, and from this wider margin the lips may be cut and struck up. In the construction illustrated in Fig. l the lips are separated by recesses b, cut out of the wide margin. Each lip is then struck up at its outer edge, so that its end shall project inwardly, and this struck-up portion presents somewhat the appearance of a shelf pitched in the direction opposite to that of the pitch of the whole screen. Thus in the construction illustrated the right end of the segment is the higher. The material therefore would travel from that end toward the opposite end. When caught, however, bythe inwardly-projecting lips B', it would be deflected from this line of travel and turned in the opposite direction over the surface of the next adjacent screen.

The object in separating the lips B by the recesses b', Figs. l and 3, is to avoid the choking of said lips by large particles of the material being screened.` Where the screen is designed to receive small particles, however, these recesses may be omitted, as in Figs. 2 and 4.

It is not essential that the deflecting-lips be formed integral with the screening-surface, as I may, if desired, make them separate therefrom and capable of attachment thereto by bolts, rivets, or other suitable means. Where such a construction is employed, the

segments may be either butt-jointed, as shown in Fig. 5, or lapped, as shown in Fig. 6.

I regard the feature of deiiecting the material from its line of travel and throwing it back upon the surface of other screen-segments in the same round as of great importance. Thishasnotbeen accomplishedbythe so-called tumblers heretofore employed, the action of which at best has been to tumble or agitate the material along straight lines extending across each round of segments.

In a screen provided by the construction above described the material is of course separated to a considerable extent while passing over the mesh. Vhen, owing to the revolution of the screen, the mass is caught by the inturned lips and deflected or turned back over a portion of the next adjacent segment, this material is again passed over a mesh of the same size, and such particles as escaped separation during the passage of the mass over the first segment are separated during the subsequent passage of the mass over the -next segment or segments.

I do not desire to limit myself to the use of deiiecting media in any particular location upon the segment or screen-jacket, as I may, if desired, place such deliecting media in the body of the mesh.

Having now described the invention, what I desire to secure by Letters Patent isl. As anew article of man ufacture,a screensegment having inturned, inclined separated lips along one edge,substanti ally as described.

2. A screen-segment curved inwardly near one edge to form a shoulder and provided with inturned, separated, inclined lips, substantially as described.

3. An inclined revoluble screen provided with a perforated segment having internal lips pitched in a direction opposed to the general pit-ch or incline of the screen, substantially as described.

'4a. An inclined revoluble screen provided with a perforated segment having internal, separated lips pitched in a direction opposed to the general pitch or incline of the screen, substantially as described.

5. A screening-surface having imperforate margins, one of said margins being curved inwardly to form a shoulder and provided with inturned separated lips, substantially as described.

6. A screening-surface having imperforate margins, one of said margins being curved inwardly to form a shoulder and provided with inturned separated lips, said lips being pitched in a Idirection opposite to the pitch of the screen upon which such segment is mounted, substantially as set forth.

This specification signed and witnessed this 31st day of July, 1896.

GEORGE W. CROSS.

Witnesses:

L. M. SMITH, p W. T. OoLvILLE.

IIO 

